The disclosed technology relates to lubricants containing quaternary ammonium compounds, particularly useful in driveline applications such as dual clutch transmissions. The quaternary ammonium compound comprises a quaternary ammonium salt such as that of a hydrocarbyl succinimide.
Transmissions may include automatic transmissions as well as dual clutch transmissions, the latter also known as double clutch or twin clutch transmissions, of a variety of types are known. For example, “Transmission Options,” in Automotive Engineering International, July, 2001, discusses on pages 67-68 double-clutch transmissions and certain of their limitations. The present invention seeks to fulfill the requirements of smooth and efficient lubrication of a driveline device, including an automatic transmission such as, in particular, a dual clutch transmission (“DCT”). A single lubricant, as described herein, simultaneously satisfies the multiple requirements of such a transmission, including lubrication of gearing, typical of a manual transmission, and lubrication of gear synchronizers, also typical of a manual transmission, while also lubricating a wet clutch component, such as a slipping start-up clutch, which is characteristic of an automatic transmission with all the challenging requirements associated therewith. In particular, the gears of the DCT require pitting protection; the synchronizers require a fluid that provides good durability of shifting as well as having the proper friction curve parameters; and the clutches for two parallel input shafts containing the gears require proper lubrication. The lubricant should also have good corrosion performance, that is, not lead to excessive corrosion of copper-containing parts with which it may come in contact.
U.S. Pat. No. 6,528,458, Tipton et al., Mar. 4, 2003, discloses a method for lubricating a dual clutch transmission. The lubricating composition comprises, among other components, oil, a friction modifier, and a dispersant such as (among others) succinimide dispersants.
U.S. Pat. No. 8,153,570, Apr. 10, 2012, and U.S. Pat. No. 8,476,207, Jul. 2, 2013, Barton et al., disclose quaternary ammonium salt detergents for use in lubricating compositions or fuels. Example 2 discloses the reaction product of a dimethylaminopropylamine succinimide with dimethyl sulphate to result in a quaternary ammonium salt.
U.S. Publication 2012/0247514, Butke et al., Oct. 4, 2012, discloses a lubricant system clean-up composition comprising a dispersant component comprising a succinimide dispersant and/or a quaternary ammonium salt dispersant. It may be used in a hydraulic system. The quaternizing agent may be, among others, dialkyl sulfates.
U.S. Publication 2008/0113890, Moreton et al., May 15, 2008, discloses a quaternary ammonium salt detergent made from the reaction product of the reaction of (a) polyalkene-substituted amine having at least one tertiary amino group; and (b) a quaternizing agent; and its use in a fuel composition. The quaternizing agent may be a dialkyl sulfate. An engine may be lubricated by an oil of lubricating viscosity and the quaternary ammonium salt.
U.S. Pat. No. 4,171,959, Vartanian, Oct. 23, 1979, discloses fuel compositions containing quaternary ammonium salts of succinimides. The X anion may be the anion of an acid, i.e., a halide or organic acid such as sulfonate or carboxylate.
U.S. Pat. No. 5,254,138, Kurek, Oct. 19, 1993, discloses a fuel composition containing a quaternary ammonium salt. There appears to be a quaternized succinimide material wherein the anion Z− may be, among others, methylsulfate.
U.S. Publication 2012/0101012, Delbridge, Apr. 26, 2012, discloses ashless or reduced ash quaternary detergents as a lubricant additive component for internal combustion engines. Use of the material to lubricate a driveline component (e.g., automatic or manual transmission) is mentioned.
U.S. Publication 2007/0155636, de Vries, Jul. 5, 2007, discloses a lubricating oil additive and lubricating oil composition with good cleaning performance. The additive is a quaternary ammonium salt having a base number of at least 10. The lubricating oil composition can be used in internal combustion engine lubricating oil, driving system lubricating oil (such as manual transmission oil, differential gear oil, or automatic transmission oil) or others.
U.S. Pat. No. 3,749,695, de Vries, Jul. 31, 1973, discloses lubricating compositions containing effective detergents and dispersants which are the reaction products of hydrocarbyl-substituted polyamines or succinimides with alkane sultones. The lubricating compositions are used in internal combustion engines.